Humanin is a 24 amino-acid peptide that is best known for its neuroprotective effects in Alzheimer's disease. In our pilot studies, we showed that humanin can protect against ischemia/reperfusion injury in mice pretreated with humanin 15 minutes before ischemia. The mechanism behind these cardioprotective effects is not clear, but our first hypothesis is that the effects of humanin are mediated by the activation of a G- protein-coupled receptor (GPCR) and PLC[unreadable]. This activation, in turn, leads to the activation of two pathways, one involving PKC and ATP-sensitive potassium channels, and the other involving PI3K and Akt. Our second hypothesis is that humanin is novel angiogenic factor and its angiogenic effect is mediated by PI3K/Akt pathway. Our specific aims are: 1.1) To determine the effective dose and optimal time of humanin administration that confers myocardial protection; 1.2) To assess the role of the GPCR/PLC[unreadable]/PKC/mitoKATP channel pathway in the preconditioning effect of humanin; 1.3) To examine the role of the PI3K/Akt survival pathway in the anti-apoptotic action of humanin; 2.1) To assess the role of the PI3K/Akt pathway in the angiogenic effect of humanin; 2.2) To identify the angiogenic genes induced by humanin in mouse heart- derived endothelial cells; 2.3) To examine the effect of humanin in neovascularization in infarcted myocardium. Clinically, humanin has a number of attractive properties as a potential therapeutic agent. For example, as an endogenous peptide, it should have minimal side effects. In addition, humanin has a delayed cardioprotective effect, which would be of great benefit for patients undergoing procedures in which cardiac arrest is necessary. Finally, the angiogenic effect of humanin may promote neovascularization in the damaged myocardium, improving the function of the heart. The information generated in this study will ultimately help explore the possibility of using humanin as a novel treatment for heart disease. Pr 400,000 people die every year from ischemic heart disease; as such, the search for new cardioprotective agents is of utmost importance. Our study is designed to provide information that will be important for the development of humanin as a therapeutic agent. Humanin has three main properties that would make it an excellent therapeutic agent. First, it is a naturally occurring hormone that should have minimal side effects. Second, humanin has a delayed cardioprotective effect, which would be useful for patients in which cardiac arrest is needed (e.g. coronary bypass). Finally, humanin has the potential to promote new blood vessel formation in damaged myocardium. [unreadable] [unreadable] [unreadable]